BEE FREE BEE Bachelor of Electrical Engineering Engineering Electromagnetics Fundamentals Questions and Answers 3

Question 1

What is the Poynting vector S for an electromagnetic wave with electric field E and magnetic field H?

Accepted Answer

E × H

Answer

The Poynting vector S = E × H represents the directional power flux density of an electromagnetic wave.

Question 2

According to the Biot-Savart law, the magnetic field dB due to a current element Idl at distance r is proportional to which quantity?

Accepted Answer

Idl × r̂ / r²

Answer

The Biot-Savart law states dB = (μ₀/4π)(Idl × r̂)/r², showing an inverse-square dependence on distance.

Question 3

A 5 cm radius circular loop carries 2 A of current. What is the approximate magnetic dipole moment magnitude?

Accepted Answer

15.7 × 10⁻³ A·m²

Answer

The magnetic dipole moment m = IA = 2 × π × (0.05)² ≈ 15.7 × 10⁻³ A·m².

Question 4

What does Ampère's circuital law with Maxwell's correction add to the original formulation?

Accepted Answer

Displacement current density ∂D/∂t

Answer

Maxwell added the displacement current term ∂D/∂t to Ampère's law, enabling it to account for time-varying electric fields.

Question 5

In a rectangular waveguide operating in the TE₁₀ mode, where does the electric field have its maximum amplitude across the broad wall dimension a?

Accepted Answer

At the center (x = a/2)

Answer

In the TE₁₀ mode, the electric field follows a half-sine distribution and reaches maximum at the center of the broad wall.

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